Divergent responses to warming of two common co-occurring Mediterranean bryozoans

Climate change threatens the structure and function of marine ecosystems, highlighting the importance of understanding the response of species to changing environmental conditions. However, thermal tolerance determining the vulnerability to warming of many abundant marine species is still poorly understood.

This study quantified in the field the effect of a temperature anomaly recorded in the Mediterranean Sea during the summer of 2015 on populations of two common bryozoans, Myriapora truncata and Pentapora fascialis. In addition, the thermal tolerance of these species was experimentally assessed in aquaria conditions.

The results of the study showed differences between species in survival patterns in natural populations, P. fascialis showing significantly lower survival rates than M. truncata. Thermotolerance experiments supported field observations: P. fascialis started to show signs of necrosis when the temperature was raised to 25-26ºC and completely died between 28-29ºC.

The authors highlight the importance of combining multiple approaches to assess the vulnerability of benthic species in a changing climate world.